"""
The MIT License (MIT)

Copyright (c) 2015-present Rapptz

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
"""

from __future__ import annotations
from typing import Callable, Dict, Iterable, List, Optional, Union, TYPE_CHECKING
import time
import asyncio

from .mixins import Hashable
from .abc import Messageable
from .enums import ChannelType, try_enum
from .errors import ClientException
from .utils import MISSING, parse_time, _get_as_snowflake

__all__ = (
    'Thread',
    'ThreadMember',
)

if TYPE_CHECKING:
    from .types.threads import (
        Thread as ThreadPayload,
        ThreadMember as ThreadMemberPayload,
        ThreadMetadata,
        ThreadArchiveDuration,
    )
    from .guild import Guild
    from .channel import TextChannel
    from .member import Member
    from .message import Message
    from .abc import Snowflake, SnowflakeTime
    from .role import Role
    from .permissions import Permissions
    from .state import ConnectionState


class Thread(Messageable, Hashable):
    """Represents a Discord thread.

    .. container:: operations

        .. describe:: x == y

            Checks if two threads are equal.

        .. describe:: x != y

            Checks if two threads are not equal.

        .. describe:: hash(x)

            Returns the thread's hash.

        .. describe:: str(x)

            Returns the thread's name.

    .. versionadded:: 2.0

    Attributes
    -----------
    name: :class:`str`
        The thread name.
    guild: :class:`Guild`
        The guild the thread belongs to.
    id: :class:`int`
        The thread ID.
    parent_id: :class:`int`
        The parent :class:`TextChannel` ID this thread belongs to.
    owner_id: :class:`int`
        The user's ID that created this thread.
    last_message_id: Optional[:class:`int`]
        The last message ID of the message sent to this thread. It may
        *not* point to an existing or valid message.
    slowmode_delay: :class:`int`
        The number of seconds a member must wait between sending messages
        in this thread. A value of `0` denotes that it is disabled.
        Bots and users with :attr:`~Permissions.manage_channels` or
        :attr:`~Permissions.manage_messages` bypass slowmode.
    message_count: :class:`int`
        An approximate number of messages in this thread. This caps at 50.
    member_count: :class:`int`
        An approximate number of members in this thread. This caps at 50.
    me: Optional[:class:`ThreadMember`]
        A thread member representing yourself, if you've joined the thread.
        This could not be available.
    archived: :class:`bool`
        Whether the thread is archived.
    locked: :class:`bool`
        Whether the thread is locked.
    archiver_id: Optional[:class:`int`]
        The user's ID that archived this thread.
    auto_archive_duration: :class:`int`
        The duration in minutes until the thread is automatically archived due to inactivity.
        Usually a value of 60, 1440, 4320 and 10080.
    archive_timestamp: :class:`datetime.datetime`
        An aware timestamp of when the thread's archived status was last updated in UTC.
    """

    __slots__ = (
        'name',
        'id',
        'guild',
        '_type',
        '_state',
        '_members',
        'owner_id',
        'parent_id',
        'last_message_id',
        'message_count',
        'member_count',
        'slowmode_delay',
        'me',
        'locked',
        'archived',
        'archiver_id',
        'auto_archive_duration',
        'archive_timestamp',
    )

    def __init__(self, *, guild: Guild, data: ThreadPayload):
        self._state: ConnectionState = guild._state
        self.guild = guild
        self._members: Dict[int, ThreadMember] = {}
        self._from_data(data)

    async def _get_channel(self):
        return self

    def __repr__(self) -> str:
        return (
            f'<Thread id={self.id!r} name={self.name!r} parent={self.parent}'
            f' owner_id={self.owner_id!r} locked={self.locked} archived={self.archived}>'
        )

    def __str__(self) -> str:
        return self.name

    def _from_data(self, data: ThreadPayload):
        self.id = int(data['id'])
        self.parent_id = int(data['parent_id'])
        self.owner_id = int(data['owner_id'])
        self.name = data['name']
        self._type = try_enum(ChannelType, data['type'])
        self.last_message_id = _get_as_snowflake(data, 'last_message_id')
        self.slowmode_delay = data.get('rate_limit_per_user', 0)
        self._unroll_metadata(data['thread_metadata'])

        try:
            member = data['member']
        except KeyError:
            self.me = None
        else:
            self.me = ThreadMember(self, member)

    def _unroll_metadata(self, data: ThreadMetadata):
        self.archived = data['archived']
        self.archiver_id = _get_as_snowflake(data, 'archiver_id')
        self.auto_archive_duration = data['auto_archive_duration']
        self.archive_timestamp = parse_time(data['archive_timestamp'])
        self.locked = data.get('locked', False)

    def _update(self, data):
        try:
            self.name = data['name']
        except KeyError:
            pass

        try:
            self._unroll_metadata(data['thread_metadata'])
        except KeyError:
            pass

    @property
    def parent(self) -> Optional[TextChannel]:
        """Optional[:class:`TextChannel`]: The parent channel this thread belongs to."""
        return self.guild.get_channel(self.parent_id)

    @property
    def owner(self) -> Optional[Member]:
        """Optional[:class:`Member`]: The member this thread belongs to."""
        return self.guild.get_member(self.owner_id)

    @property
    def last_message(self) -> Optional[Message]:
        """Fetches the last message from this channel in cache.

        The message might not be valid or point to an existing message.

        .. admonition:: Reliable Fetching
            :class: helpful

            For a slightly more reliable method of fetching the
            last message, consider using either :meth:`history`
            or :meth:`fetch_message` with the :attr:`last_message_id`
            attribute.

        Returns
        ---------
        Optional[:class:`Message`]
            The last message in this channel or ``None`` if not found.
        """
        return self._state._get_message(self.last_message_id) if self.last_message_id else None

    @property
    def category_id(self) -> Optional[int]:
        """The category channel ID the parent channel belongs to, if applicable.

        Raises
        -------
        ClientException
            The parent channel was not cached and returned ``None``.

        Returns
        -------
        Optional[:class:`int`]
            The parent channel's category ID.
        """

        parent = self.parent
        if parent is None:
            raise ClientException('Parent channel not found')
        return parent.category_id

    def is_private(self) -> bool:
        """:class:`bool`: Whether the thread is a private thread.

        A private thread is only viewable by those that have been explicitly
        invited or have :attr:`~.Permissions.manage_threads`.
        """
        return self._type is ChannelType.private_thread

    def is_news(self) -> bool:
        """:class:`bool`: Whether the thread is a news thread.

        A news thread is a thread that has a parent that is a news channel,
        i.e. :meth:`.TextChannel.is_news` is ``True``.
        """
        return self._type is ChannelType.news_thread

    def permissions_for(self, obj: Union[Member, Role], /) -> Permissions:
        """Handles permission resolution for the :class:`~discord.Member`
        or :class:`~discord.Role`.

        Since threads do not have their own permissions, they inherit them
        from the parent channel. This is a convenience method for
        calling :meth:`~discord.TextChannel.permissions_for` on the
        parent channel.

        Parameters
        ----------
        obj: Union[:class:`~discord.Member`, :class:`~discord.Role`]
            The object to resolve permissions for. This could be either
            a member or a role. If it's a role then member overwrites
            are not computed.

        Raises
        -------
        ClientException
            The parent channel was not cached and returned ``None``

        Returns
        -------
        :class:`~discord.Permissions`
            The resolved permissions for the member or role.
        """

        parent = self.parent
        if parent is None:
            raise ClientException('Parent channel not found')
        return parent.permissions_for(obj)

    async def delete_messages(self, messages: Iterable[Snowflake]) -> None:
        """|coro|

        Deletes a list of messages. This is similar to :meth:`Message.delete`
        except it bulk deletes multiple messages.

        As a special case, if the number of messages is 0, then nothing
        is done. If the number of messages is 1 then single message
        delete is done. If it's more than two, then bulk delete is used.

        You cannot bulk delete more than 100 messages or messages that
        are older than 14 days old.

        You must have the :attr:`~Permissions.manage_messages` permission to
        use this.

        Usable only by bot accounts.

        Parameters
        -----------
        messages: Iterable[:class:`abc.Snowflake`]
            An iterable of messages denoting which ones to bulk delete.

        Raises
        ------
        ClientException
            The number of messages to delete was more than 100.
        Forbidden
            You do not have proper permissions to delete the messages or
            you're not using a bot account.
        NotFound
            If single delete, then the message was already deleted.
        HTTPException
            Deleting the messages failed.
        """
        if not isinstance(messages, (list, tuple)):
            messages = list(messages)

        if len(messages) == 0:
            return  # do nothing

        if len(messages) == 1:
            message_id = messages[0].id
            await self._state.http.delete_message(self.id, message_id)
            return

        if len(messages) > 100:
            raise ClientException('Can only bulk delete messages up to 100 messages')

        message_ids = [m.id for m in messages]
        await self._state.http.delete_messages(self.id, message_ids)

    async def purge(
        self,
        *,
        limit: int = 100,
        check: Callable[[Message], bool] = MISSING,
        before: Optional[SnowflakeTime] = None,
        after: Optional[SnowflakeTime] = None,
        around: Optional[SnowflakeTime] = None,
        oldest_first: Optional[bool] = False,
        bulk: bool = True,
    ) -> List[Message]:
        """|coro|

        Purges a list of messages that meet the criteria given by the predicate
        ``check``. If a ``check`` is not provided then all messages are deleted
        without discrimination.

        You must have the :attr:`~Permissions.manage_messages` permission to
        delete messages even if they are your own (unless you are a user
        account). The :attr:`~Permissions.read_message_history` permission is
        also needed to retrieve message history.

        Examples
        ---------

        Deleting bot's messages ::

            def is_me(m):
                return m.author == client.user

            deleted = await thread.purge(limit=100, check=is_me)
            await thread.send(f'Deleted {len(deleted)} message(s)')

        Parameters
        -----------
        limit: Optional[:class:`int`]
            The number of messages to search through. This is not the number
            of messages that will be deleted, though it can be.
        check: Callable[[:class:`Message`], :class:`bool`]
            The function used to check if a message should be deleted.
            It must take a :class:`Message` as its sole parameter.
        before: Optional[Union[:class:`abc.Snowflake`, :class:`datetime.datetime`]]
            Same as ``before`` in :meth:`history`.
        after: Optional[Union[:class:`abc.Snowflake`, :class:`datetime.datetime`]]
            Same as ``after`` in :meth:`history`.
        around: Optional[Union[:class:`abc.Snowflake`, :class:`datetime.datetime`]]
            Same as ``around`` in :meth:`history`.
        oldest_first: Optional[:class:`bool`]
            Same as ``oldest_first`` in :meth:`history`.
        bulk: :class:`bool`
            If ``True``, use bulk delete. Setting this to ``False`` is useful for mass-deleting
            a bot's own messages without :attr:`Permissions.manage_messages`. When ``True``, will
            fall back to single delete if messages are older than two weeks.

        Raises
        -------
        Forbidden
            You do not have proper permissions to do the actions required.
        HTTPException
            Purging the messages failed.

        Returns
        --------
        List[:class:`.Message`]
            The list of messages that were deleted.
        """

        if check is MISSING:
            check = lambda m: True

        iterator = self.history(limit=limit, before=before, after=after, oldest_first=oldest_first, around=around)
        ret: List[Message] = []
        count = 0

        minimum_time = int((time.time() - 14 * 24 * 60 * 60) * 1000.0 - 1420070400000) << 22

        async def _single_delete_strategy(messages: Iterable[Message]):
            for m in messages:
                await m.delete()

        strategy = self.delete_messages if bulk else _single_delete_strategy

        async for message in iterator:
            if count == 100:
                to_delete = ret[-100:]
                await strategy(to_delete)
                count = 0
                await asyncio.sleep(1)

            if not check(message):
                continue

            if message.id < minimum_time:
                # older than 14 days old
                if count == 1:
                    await ret[-1].delete()
                elif count >= 2:
                    to_delete = ret[-count:]
                    await strategy(to_delete)

                count = 0
                strategy = _single_delete_strategy

            count += 1
            ret.append(message)

        # SOme messages remaining to poll
        if count >= 2:
            # more than 2 messages -> bulk delete
            to_delete = ret[-count:]
            await strategy(to_delete)
        elif count == 1:
            # delete a single message
            await ret[-1].delete()

        return ret

    async def edit(
        self,
        *,
        name: str = MISSING,
        archived: bool = MISSING,
        locked: bool = MISSING,
        slowmode_delay: int = MISSING,
        auto_archive_duration: ThreadArchiveDuration = MISSING,
    ):
        """|coro|

        Edits the thread.

        Editing the thread requires :attr:`.Permissions.manage_threads`. The thread
        creator can also edit ``name``, ``archived`` or ``auto_archive_duration``.
        Note that if the thread is locked then only those with :attr:`.Permissions.manage_threads`
        can unarchive a thread.

        The thread must be unarchived to be edited.

        Parameters
        ------------
        name: :class:`str`
            The new name of the thread.
        archived: :class:`bool`
            Whether to archive the thread or not.
        locked: :class:`bool`
            Whether to lock the thread or not.
        auto_archive_duration: :class:`int`
            The new duration to auto archive threads for inactivity.
            Must be one of ``60``, ``1440``, ``4320``, or ``10080``.
        slowmode_delay: :class:`int`
            Specifies the slowmode rate limit for user in this thread, in seconds.
            A value of ``0`` disables slowmode. The maximum value possible is ``21600``.

        Raises
        -------
        Forbidden
            You do not have permissions to edit the thread.
        HTTPException
            Editing the thread failed.
        """
        payload = {}
        if name is not MISSING:
            payload['name'] = str(name)
        if archived is not MISSING:
            payload['archived'] = archived
        if auto_archive_duration is not MISSING:
            payload['auto_archive_duration'] = auto_archive_duration
        if locked is not MISSING:
            payload['locked'] = locked
        if slowmode_delay is not MISSING:
            payload['rate_limit_per_user'] = slowmode_delay

        await self._state.http.edit_channel(self.id, **payload)

    async def join(self):
        """|coro|

        Joins this thread.

        You must have :attr:`~Permissions.send_messages` and :attr:`~Permissions.use_threads`
        to join a public thread. If the thread is private then :attr:`~Permissions.send_messages`
        and either :attr:`~Permissions.use_private_threads` or :attr:`~Permissions.manage_messages`
        is required to join the thread.

        Raises
        -------
        Forbidden
            You do not have permissions to join the thread.
        HTTPException
            Joining the thread failed.
        """
        await self._state.http.join_thread(self.id)

    async def leave(self):
        """|coro|

        Leaves this thread.

        Raises
        -------
        HTTPException
            Leaving the thread failed.
        """
        await self._state.http.leave_thread(self.id)

    async def add_user(self, user: Snowflake):
        """|coro|

        Adds a user to this thread.

        You must have :attr:`~Permissions.send_messages` and :attr:`~Permissions.use_threads`
        to add a user to a public thread. If the thread is private then :attr:`~Permissions.send_messages`
        and either :attr:`~Permissions.use_private_threads` or :attr:`~Permissions.manage_messages`
        is required to add a user to the thread.

        Parameters
        -----------
        user: :class:`abc.Snowflake`
            The user to add to the thread.

        Raises
        -------
        Forbidden
            You do not have permissions to add the user to the thread.
        HTTPException
            Adding the user to the thread failed.
        """
        await self._state.http.add_user_to_thread(self.id, user.id)

    async def remove_user(self, user: Snowflake):
        """|coro|

        Removes a user from this thread.

        You must have :attr:`~Permissions.manage_threads` or be the creator of the thread to remove a user.

        Parameters
        -----------
        user: :class:`abc.Snowflake`
            The user to add to the thread.

        Raises
        -------
        Forbidden
            You do not have permissions to remove the user from the thread.
        HTTPException
            Removing the user from the thread failed.
        """
        await self._state.http.remove_user_from_thread(self.id, user.id)

    async def delete(self):
        """|coro|

        Deletes this thread.

        You must have :attr:`~Permissions.manage_threads` to delete threads.

        Raises
        -------
        Forbidden
            You do not have permissions to delete this thread.
        HTTPException
            Deleting the thread failed.
        """
        await self._state.http.delete_channel(self.id)

    def _add_member(self, member: ThreadMember) -> None:
        self._members[member.id] = member

    def _pop_member(self, member_id: int) -> Optional[ThreadMember]:
        return self._members.pop(member_id, None)


class ThreadMember(Hashable):
    """Represents a Discord thread member.

    .. container:: operations

        .. describe:: x == y

            Checks if two thread members are equal.

        .. describe:: x != y

            Checks if two thread members are not equal.

        .. describe:: hash(x)

            Returns the thread member's hash.

        .. describe:: str(x)

            Returns the thread member's name.

    .. versionadded:: 2.0

    Attributes
    -----------
    id: :class:`int`
        The thread member's ID.
    thread_id: :class:`int`
        The thread's ID.
    joined_at: :class:`datetime.datetime`
        The time the member joined the thread in UTC.
    """

    __slots__ = (
        'id',
        'thread_id',
        'joined_at',
        'flags',
        '_state',
        'parent',
    )

    def __init__(self, parent: Thread, data: ThreadMemberPayload):
        self.parent = parent
        self._state = parent._state
        self._from_data(data)

    def __repr__(self) -> str:
        return f'<ThreadMember id={self.id} thread_id={self.thread_id} joined_at={self.joined_at!r}>'

    def _from_data(self, data: ThreadMemberPayload):
        try:
            self.id = int(data['user_id'])
        except KeyError:
            assert self._state.self_id is not None
            self.id = self._state.self_id

        try:
            self.thread_id = int(data['id'])
        except KeyError:
            self.thread_id = self.parent.id

        self.joined_at = parse_time(data['join_timestamp'])
        self.flags = data['flags']

    @property
    def thread(self) -> Thread:
        """:class:`Thread`: The thread this member belongs to."""
        return self.parent
